Democrats could be headed for the first ‘brokered convention’ in 56 years. What happens if neither Barack Obama nor Hillary Clinton has it all sewn up by August?

Aren’t nominating conventions just meaningless rituals?They certainly have been for the past 40 years. But it was once common for candidates actually to be chosen on the convention floor. At the earliest conventions, back in the 1830s, delegates were appointed by party leaders, not voters. Delegates could support any candidate they liked. Since that practice continued throughout the 19th century, conventions were often marked by frenzied horse-trading and political intrigue. In 1904, a few states began holding primaries to elect delegates pledged to specific candidates, but this remained the exception until the 1970s; most delegates were appointed and unpledged. If the party failed to cohere around a single, obvious candidate in the first round of voting, the party faced a “brokered convention.”

How does a brokered convention work?Even today, when most convention delegates are pledged to a candidate, that commitment is only binding for the first round. After that, delegates can vote for whomever they please, and the convention becomes “brokered.” That’s when the deal-making, or “brokering,’’ starts. In the past, rival factions would attempt to sway delegates by offering Cabinet positions, platform planks, and other incentives. “In some cases,” says historian Michael Beschloss, “managers were making promises in the candidate’s name that the candidate didn’t even know about.” Often, party bosses would hammer out deals in “smoke-filled rooms”—a term coined in 1920 after Republican bigwigs emerged from Chicago’s Blackstone Hotel backing the little-known Warren Harding. The last brokered conventions were in 1948 for the Republicans and 1952 for the Democrats.

Have conventions been calm since then?Hardly. In 1976, President Gerald Ford went into the Republican convention with a slim lead over Ronald Reagan. Before the balloting began, both candidates were feverishly wooing delegates, calling in favors and making promises. “We had the incumbency,” says Ford aide Stuart Spencer, “the goodies, like Air Force One rides and coming to the White House for dinner.” Ford held on, but barely. At the 1980 Democratic convention, Ted Kennedy tried in vain to get Jimmy Carter’s delegates to come over to him. But the most contentious modern convention was the 1968 Democratic convention in Chicago. The party’s liberal, anti-war wing backed Eugene McCarthy, but delegates gave the nomination to Hubert Humphrey, who hadn’t won a single primary.

How did people react?It was chaos. Anti-war activists staged massive protests outside the convention, which devolved into riots when police moved in with tear gas and batons. The debacle shamed the party, which then instituted reforms to transfer power from insiders to grass-roots voters. But for the next two elections, Democratic delegates selected two anti-establishment outsiders, George McGovern and Carter, and the pendulum swung again. “There was a view that the Democratic Party had allowed the grass roots to become too empowered,” says Meredith McGehee of the Campaign Legal Center, “and that people whose job it was to get Democrats elected were being shut out.” So the party created a new class of delegates—superdelegates—who would be picked by virtue of their insider status (see below). This year, about 20 percent of Democratic delegates will be superdelegates. They can vote however they choose, though Obama, now leading in the popular vote and delegate count, has been arguing that superdelegates should follow “the will of the people.”

What else can influence nomination battles?A lot depends on which delegates are actually allowed to vote. This year, the Democratic Party stripped Florida and Michigan delegates of their credentials because those states violated a party rule against holding primaries before Feb. 5. Clinton won those states, and she now says their delegations should get their credentials back. If the issue isn’t settled prior to the convention, a credentials fight could break out—the first since 1972, when anti-McGovern Democrats attempted to block him from seating his delegates. The Credentials Committee—comprising representatives of each state delegation and various party appointees—would make a recommendation to the full convention, which would vote on it. Given that most participants would be Clinton or Obama loyalists, it’s unlikely to be a calm, reasoned debate.

What if neither candidate wins the first round?“It would be wild,” says Stuart Spencer, the former Ford advisor. But it’s hard to say exactly what a brokered convention would look like today, because politics have changed so much in the past 50 years. There are no longer all-powerful party bosses who can ram through backroom deals. Instead, spin doctors are likely to fight their battles in the press. The 1976 GOP convention may be instructive: Reagan shocked the convention and the press by naming his running mate prior to the balloting. The move was calculated to pressure Ford into naming his own vice president—which would have alienated one faction or another. Ford didn’t take the bait.

How likely is a brokered Democratic convention this year?Not very, most analysts say, because it could prove so damaging to the nominee. A brokered convention, history suggests, exposes intra-party divisions that don’t heal before November. (The last candidate to win the White House after a brokered convention was Franklin Roosevelt, in 1932.) “I don’t think we can afford to have a brokered convention,” Democratic Party Chairman Howard Dean said recently. If a winner doesn’t emerge from the primaries, he said, “we’re going to have to get the candidates together and make some kind of an arrangement.” But Dean has no power to impose a remedy, and if the candidates insist on fighting it out in the Credentials Committee and on the floor, it could get ugly. “If you think 1968 was bad, you watch,” said former Virginia Gov. Doug Wilder, an Obama supporter. “In 2008, it could be worse.”

All eyes on the superdelegates:Neither Obama nor Clinton is expected to enter the August convention in Denver with enough elected delegates to secure a first-round win. That means the balance of power will be held by 796 superdelegates. For weeks, Clinton and Obama have been wooing them with calls from surrogates such as Bill Clinton and Michelle Obama and, in some cases, visits with the candidates themselves. So who are they? Every Democratic member of Congress is a superdelegate, as are all Democratic governors. Twenty are elder statesmen, such as Jimmy Carter and Al Gore. But most are ordinary citizens like Wyoming ophthalmologist John Millin, who became a member of the Democratic National Committee through his involvement in local politics. “I don’t think any of us got into this,” Millin says, “thinking we would be part of a small group of people who get to select the next president of the United States.”